st: Re: combining two variables

["Michael Blasnik" <michael.blasnik@verizon.net>]

If all of the vars that begin a_ have a matching b_ var, and all are 
numeric, then you could try something like

foreach var in varlist a_* {
local stub=substr("`var'",3,.)
gen c_`stub'=cond(b_`stub'==.,`var',b_`stub')
}

If the data come from different datasets, you might want to look at -merge- 
with the update option.

Michael Blasnik

p.s. For proper Statalist etiquette, avoid saying things like  "i have been 
trying to figure out a way to do this with the foreach command.  but it 
doesn't seem to be working out."  Instead, you should show us what you typed 
and why "it didn't work out."


----- Original Message ----- 
From: "Daphna Bassok" <dbassok@stanford.edu>
To: <statalist@hsphsun2.harvard.edu>
Sent: Thursday, February 02, 2006 7:13 PM
Subject: st: combining two variables



> hi all-
>
> i have a data structure question, and i could use some advice.
>
> suppose i have two variables say a_school and b_school.  the values of 
> these two variables are either the same, or one of the two might be 
> missing. i would like to somehow merge these into a single variable- say 
> c_school.
>
> if i only had to do this once, it would be quite simple.
>
> gen c_school=b_school
> replace  c_school=a_school if c_school==.
>
> done.
>
> however, i have to do this repeatedly.  as in... i have many of these 
> pairs. a_size, b_size... a_score, b_score...etc.
>
>
> >
> does anyone have any suggestions?
>
> any help would be appreciated.
>
> daphna
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